A catalog of openly-licensed textbooks, many with reviews from college instructors.
Free, open-source, peer-reviewed college textbooks primarily for introductory courses in science, math, economics, psychology, and sociology.
Open educational resources from leading colleges and universities, including textbooks.
Monographs and textbooks primarily in the humanities and social sciences.
A clearinghouse of member-submitted learning materials, including textbooks, exercises, presentations, etc.
Clearinghouse of OERs.
OSUL Copyright Resources Center Guide to Finding Public Domain and Openly Licensed Materials